     [this]
     (when-not (satisfies? store/BlockStore primary)
       (throw (IllegalStateException.
-               (str "Buffer block store cannot start without a primary block store: "
+               (str "Cannot start buffer block store without a backing primary store: "
                     (pr-str primary)))))
     (when-not (satisfies? store/BlockStore buffer)
       (throw (IllegalStateException.
-               (str "Buffer block store cannot start without a buffer block store: "
+               (str "Cannot start buffer block store without a backing buffer store: "
                     (pr-str buffer)))))
     this)
 



(defn buffer-block-store
  "Creates a new buffering block store.

  - `:buffer`
    Block store to use for new writes.



(defn flush!
  "Flush the store, writing all buffered blocks to the primary store. Returns a
  deferred which yields a summary of the flushed blocks."
  [store]
  (->>
    (block/list (:buffer store))
